Properties of a complex technical system (denoted in general below as “function unit”) can frequently be stipulated by a multiplicity of input variables, that is to say in a multidimensional parameter space. It is often difficult and wearisome for the user to find a suitable value combination (also denoted below as “control state” or “value tuple”) in such a parameter space, the more so as the number of possible control states, and the dimensionality of the parameter space, increases as a power of the dimensionality of the parameter space, and the interaction of the individual input variables with regard to the resulting behavior of the function unit often cannot be predicted by the user, particularly given a lack of experience.
Here, the function unit can be both a hardware component and a software component.
An example of such a function unit is, in particular, a software module for calculating the attractiveness of illumination of a virtual object in a three-dimensional display, in particular a so-called raytracing software. Such attractiveness of illumination is used, inter alia, in imaging medical technology in order to display realistically a three-dimensional recording of a body structure obtained, for example, by a tomographic method. Such attractiveness of illumination is parametrized, for example, by input variables that specify the intensity of the ambient light, of the diffuse reflection, of the specular reflection or of the gloss of the object to be imaged. Here, the overwhelming majority of possible control states lead as a rule to an undesirable image impression. By contrast, only a very few control states supply a satisfactory result.
A further example of such a function unit is a software package for coloring a three-dimensional volume display (VRT—volume rendering). Such methods are, in turn, frequently used in imaging medical technology in order to display three-dimensionally recorded body structures. Here, input variables in particular specify color components of red, green and blue that can be mixed by the function unit to produce a high number of possible final colors. Only very few color mixtures thereby lead in turn to a realistic color impression of a displayed body structure such as is usually desired by a medical practitioner. These “realistic” colors are, moreover, occasionally distributed irregularly in the available color spectrum.
Hardware-based examples of function units are a complex tone mixer console with a multiplicity of tone and/or frequency channels that can be combined to form an overall tone, or the control device of a complex lighting system.
In hardware-based function units, the setting of the input variables is frequently performed by way of a number of mechanical regulators (linear regulators, rotary regulators, etc.), of which each is assigned to an input variable. Particularly in the case of software-based function units, it is mostly graphic simulations of mechanical regulators within the user interface of a software program, or alphanumeric input fields that are provided for setting the input variables. In both cases, the user must search for a suitable setting for each input variable individually.
Consequently, a list of frequently used value combinations (so-called presets) is made available to the user for simplified parametrization of such a function unit. In the case of a color selection module, such a preset list includes, for example, value combinations for a number of standard colors.
Such a discrete value list leads to a significant simplification of the parametrizing process particularly when only a few selection possibilities are prescribed. As a result, however, the freedom of choice of a user to set an individual result is necessarily restricted. On the other hand, if a large quantity of possible value combinations is prescribed, this in turn necessarily complicates the selection process.